using namespace llvm;
using namespace PatternMatch;
+#define DEBUG_TYPE "instcombine"
+
/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
/// is to leave as a vector operation. isConstant indicates whether we're
/// extracting one known element. If false we're extracting a variable index.
if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
// If this is an insert to a variable element, we don't know what it is.
if (!isa<ConstantInt>(III->getOperand(2)))
- return 0;
+ return nullptr;
unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
// If this is an insert to the element we are looking for, return the
}
// Extract a value from a vector add operation with a constant zero.
- Value *Val = 0; Constant *Con = 0;
+ Value *Val = nullptr; Constant *Con = nullptr;
if (match(V, m_Add(m_Value(Val), m_Constant(Con)))) {
if (Con->getAggregateElement(EltNo)->isNullValue())
return FindScalarElement(Val, EltNo);
}
// Otherwise, we don't know.
- return 0;
+ return nullptr;
}
// If we have a PHI node with a vector type that has only 2 uses: feed
Instruction *InstCombiner::scalarizePHI(ExtractElementInst &EI, PHINode *PN) {
// Verify that the PHI node has exactly 2 uses. Otherwise return NULL.
if (!PN->hasNUses(2))
- return NULL;
+ return nullptr;
// If so, it's known at this point that one operand is PHI and the other is
// an extractelement node. Find the PHI user that is not the extractelement
// otherwise return NULL.
if (!PHIUser->hasOneUse() || !(PHIUser->user_back() == PN) ||
!(isa<BinaryOperator>(PHIUser)) || !CheapToScalarize(PHIUser, true))
- return NULL;
+ return nullptr;
// Create a scalar PHI node that will replace the vector PHI node
// just before the current PHI node.
}
}
}
- return 0;
+ return nullptr;
}
/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
// Either the extracted from or inserted into vector must be RHSVec,
// otherwise we'd end up with a shuffle of three inputs.
- if (EI->getOperand(0) == PermittedRHS || PermittedRHS == 0) {
+ if (EI->getOperand(0) == PermittedRHS || PermittedRHS == nullptr) {
Value *RHS = EI->getOperand(0);
ShuffleOps LR = CollectShuffleElements(VecOp, Mask, RHS);
- assert(LR.second == 0 || LR.second == RHS);
+ assert(LR.second == nullptr || LR.second == RHS);
if (LR.first->getType() != RHS->getType()) {
// We tried our best, but we can't find anything compatible with RHS
return std::make_pair(V, nullptr);
}
+/// Try to find redundant insertvalue instructions, like the following ones:
+/// %0 = insertvalue { i8, i32 } undef, i8 %x, 0
+/// %1 = insertvalue { i8, i32 } %0, i8 %y, 0
+/// Here the second instruction inserts values at the same indices, as the
+/// first one, making the first one redundant.
+/// It should be transformed to:
+/// %0 = insertvalue { i8, i32 } undef, i8 %y, 0
+Instruction *InstCombiner::visitInsertValueInst(InsertValueInst &I) {
+ bool IsRedundant = false;
+ ArrayRef<unsigned int> FirstIndices = I.getIndices();
+
+ // If there is a chain of insertvalue instructions (each of them except the
+ // last one has only one use and it's another insertvalue insn from this
+ // chain), check if any of the 'children' uses the same indices as the first
+ // instruction. In this case, the first one is redundant.
+ Value *V = &I;
+ unsigned Depth = 0;
+ while (V->hasOneUse() && Depth < 10) {
+ User *U = V->user_back();
+ auto UserInsInst = dyn_cast<InsertValueInst>(U);
+ if (!UserInsInst || U->getOperand(0) != V)
+ break;
+ if (UserInsInst->getIndices() == FirstIndices) {
+ IsRedundant = true;
+ break;
+ }
+ V = UserInsInst;
+ Depth++;
+ }
+
+ if (IsRedundant)
+ return ReplaceInstUsesWith(I, I.getOperand(0));
+ return nullptr;
+}
+
Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
Value *VecOp = IE.getOperand(0);
Value *ScalarOp = IE.getOperand(1);
// (and any insertelements it points to), into one big shuffle.
if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.user_back())) {
SmallVector<Constant*, 16> Mask;
- ShuffleOps LR = CollectShuffleElements(&IE, Mask, 0);
+ ShuffleOps LR = CollectShuffleElements(&IE, Mask, nullptr);
// The proposed shuffle may be trivial, in which case we shouldn't
// perform the combine.
if (LR.first != &IE && LR.second != &IE) {
// We now have a shuffle of LHS, RHS, Mask.
- if (LR.second == 0) LR.second = UndefValue::get(LR.first->getType());
+ if (LR.second == nullptr)
+ LR.second = UndefValue::get(LR.first->getType());
return new ShuffleVectorInst(LR.first, LR.second,
ConstantVector::get(Mask));
}
return &IE;
}
- return 0;
+ return nullptr;
}
/// Return true if we can evaluate the specified expression tree if the vector
llvm_unreachable("failed to reorder elements of vector instruction!");
}
+static void RecognizeIdentityMask(const SmallVectorImpl<int> &Mask,
+ bool &isLHSID, bool &isRHSID) {
+ isLHSID = isRHSID = true;
+
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] < 0) continue; // Ignore undef values.
+ // Is this an identity shuffle of the LHS value?
+ isLHSID &= (Mask[i] == (int)i);
+
+ // Is this an identity shuffle of the RHS value?
+ isRHSID &= (Mask[i]-e == i);
+ }
+}
+
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
Value *LHS = SVI.getOperand(0);
Value *RHS = SVI.getOperand(1);
if (VWidth == LHSWidth) {
// Analyze the shuffle, are the LHS or RHS and identity shuffles?
- bool isLHSID = true, isRHSID = true;
-
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
- if (Mask[i] < 0) continue; // Ignore undef values.
- // Is this an identity shuffle of the LHS value?
- isLHSID &= (Mask[i] == (int)i);
-
- // Is this an identity shuffle of the RHS value?
- isRHSID &= (Mask[i]-e == i);
- }
+ bool isLHSID, isRHSID;
+ RecognizeIdentityMask(Mask, isLHSID, isRHSID);
// Eliminate identity shuffles.
if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
ShuffleVectorInst* RHSShuffle = dyn_cast<ShuffleVectorInst>(RHS);
if (LHSShuffle)
if (!isa<UndefValue>(LHSShuffle->getOperand(1)) && !isa<UndefValue>(RHS))
- LHSShuffle = NULL;
+ LHSShuffle = nullptr;
if (RHSShuffle)
if (!isa<UndefValue>(RHSShuffle->getOperand(1)))
- RHSShuffle = NULL;
+ RHSShuffle = nullptr;
if (!LHSShuffle && !RHSShuffle)
- return MadeChange ? &SVI : 0;
+ return MadeChange ? &SVI : nullptr;
- Value* LHSOp0 = NULL;
- Value* LHSOp1 = NULL;
- Value* RHSOp0 = NULL;
+ Value* LHSOp0 = nullptr;
+ Value* LHSOp1 = nullptr;
+ Value* RHSOp0 = nullptr;
unsigned LHSOp0Width = 0;
unsigned RHSOp0Width = 0;
if (LHSShuffle) {
// case 4
if (LHSOp0 == RHSOp0) {
newLHS = LHSOp0;
- newRHS = NULL;
+ newRHS = nullptr;
}
if (newLHS == LHS && newRHS == RHS)
- return MadeChange ? &SVI : 0;
+ return MadeChange ? &SVI : nullptr;
SmallVector<int, 16> LHSMask;
SmallVector<int, 16> RHSMask;
// If newRHS == newLHS, we want to remap any references from newRHS to
// newLHS so that we can properly identify splats that may occur due to
// obfuscation across the two vectors.
- if (eltMask >= 0 && newRHS != NULL && newLHS != newRHS)
+ if (eltMask >= 0 && newRHS != nullptr && newLHS != newRHS)
eltMask += newLHSWidth;
}
Elts.push_back(ConstantInt::get(Int32Ty, newMask[i]));
}
}
- if (newRHS == NULL)
+ if (!newRHS)
newRHS = UndefValue::get(newLHS->getType());
return new ShuffleVectorInst(newLHS, newRHS, ConstantVector::get(Elts));
}
- return MadeChange ? &SVI : 0;
+ // If the result mask is an identity, replace uses of this instruction with
+ // corresponding argument.
+ bool isLHSID, isRHSID;
+ RecognizeIdentityMask(newMask, isLHSID, isRHSID);
+ if (isLHSID && VWidth == LHSOp0Width) return ReplaceInstUsesWith(SVI, newLHS);
+ if (isRHSID && VWidth == RHSOp0Width) return ReplaceInstUsesWith(SVI, newRHS);
+
+ return MadeChange ? &SVI : nullptr;
}
projects / oota-llvm.git / blobdiff